The present invention relates to a control system for a semiconductor device manufacturing process and a method in which a semiconductor fabrication process program checks states set up in apparatuses required to perform the respective processes, to thereby prevent errors produced during the processes.
Generally, for the finish product, a semiconductor device passes through various processes such as mask fabrication, wafer fabrication, assembly and inspection. These processes require a variety of equipment such as digitizers, developers, diffusion furnaces, coaters, chemical vapor depositors (CVDs), automatic mounters, and testers.
These apparatuses are designed to operate under the control of a host computer. The host computer is connected to a main host computer, and receives information about the processes performed by the apparatuses, and program information from the main host computer. The apparatuses described above, for instance, the diffusion furnace or CVD, perform not only a single process but also a variety of processes modified therefrom.
It will be explained below that processes set up by different programs are carried out in a diffusion furnace (not shown).
The diffusion furnace is used to carry out diffusion, or oxidation in which an SiO.sub.2 layer is formed on a silicon wafer. Especially, in the oxidation process, the oxide layer may be formed so as to be of different thicknesses, as required for the particular instances. Programs for controlling the process of forming an oxide layer of the respective thicknesses are used to control operation of the diffusion furnace.
In FIG. 1, a program for forming an oxide layer of 3,000 .ANG. is designated PPID 1, and a program forming an oxide layer of 800.ANG. is designated PPID 2. PPID acronym equating to process program identification. There are many process conditions which must be set up in the diffusion furnace in order to perform the oxidation in accordance with the aforementioned programs. For temperature and the amount of oxygen for diffusion, PPID 1 is designed to maintain a temperature of 1,000.degree. C. and to supply of 8 l of oxygen process. In contrast, PPID 2 is designed to maintain a temperature of 900.degree. C. and to supply 10 l of oxygen.
Program instructions to perform those processes are input to the main host computer (not shown) by a user, and transferred to the host computer (not shown) and are transferred then to the diffusion furnace. If the PPID information is input, the diffusion furnace confirms receipt of the input and performs a process according to a corresponding program. These processes in accordance with the respective PPID programs may be performed alternately in a single diffusion furnace, if necessary.
In carrying out the alternate processes, when information about PPID 1 is received from the host computer, the diffusion furnace sets its process conditions to a temperature of 1,000.degree. C. and 8 l of oxygen, and then performs a process corresponding to PPID 1. After a process corresponding to PPID 1 has been performed, when information about PPID 2 is received from the host computer, a temperature of 900.degree. C. and 10 l of oxygen are fixed for the diffusion furnace's conditions. With these conditions, a process corresponding to PPID 2 is carried out.
However, when the information about the program is transmitted from the host computer to the process-performing apparatus such as the diffusion furnace in order to conduct the process within one apparatus, the transmitted information is often not received correctly, or produces an error in the process-performing apparatus such as the diffusion furnace. As a result, the PPID may not be updated to reflect the desired change, e.g., from PPID 1 to PPID 2, so that the previous PPID process is performed again, instead of the intended next one.
In addition, due to problems of software set in the process performing apparatus, the transmitted PPID may not be recognized accurately and therefore the previous PPID process may be performed. Further, due to communication trouble, the transmitted information may be deformed and transferred in such a deformed state to the process-performing apparatus. In this case, process conversion may not be carried out.
Aside from the above cases, program information transferred to carry out a process may not be received correctly in the process-performing apparatus so that not a desired process but a mutant process is performed, deteriorating the quality of products.
In order to solve the problems described above, an operator in charge of corresponding equipment confirms information and program set in the process performing apparatus frequently in order to prevent process errors. However, this is not so efficient as to accurately check, and, thus, prevent the process errors.